Researchers used laboratory simulations to recreate conditions on early Earth and discovered that the evolution of ancient proteins into all life forms on the planet, including plants, animals and humans, would not have been possible without certain amino acids. The discovery of the role of amino acids in the formation of the genetic code of ancient microorganisms sheds new light on the age-old mystery of the origin of life on Earth.
“You see the same amino acids in every organism, from humans to bacteria to archaea, and that’s because it’s linked to this tree of life, the organism that is the ancestor of all living things, which is the origin of everything on Earth,” Stephen said. Fried, a Johns Hopkins chemist who led the study with scientists from Charles University in the Czech Republic. “We explain the events that led to why this ancestor got these amino acids.”
In the lab, researchers simulated primary protein synthesis 4 billion years ago using an alternate set of amino acids that were abundant before life appeared on Earth.
They found that ancient organic compounds integrated into their biochemistry the amino acids most suitable for protein folding. In other words, life on Earth evolved not only because some amino acids were found and readily produced in ancient habitats, but also because some were particularly good at helping proteins take on certain shapes to perform important functions.
“Protein folding basically allowed us to evolve before life appeared on our planet,” Fried said. “You could have had evolution before biology, you could have had natural selection of chemicals useful for life, even before DNA.”
Although there were hundreds of amino acids on the Early Earth, all living things use the same 20 of these compounds. Fried calls these compounds “canonical”. But science has struggled to determine what is so special about these 20 amino acids.
In the first billion years, Earth’s atmosphere consisted of a number of gases, such as ammonia and carbon dioxide, that reacted with high levels of ultraviolet radiation to form some of the simpler canonical amino acids. Others came via special delivery by meteorites, who offered a mixed bag of materials that helped life on Earth complete the 10 “early” amino acid sets. How the rest was formed is an open question that Fried’s team is trying to answer with the new study, especially since these space rocks yield so much more than “modern” amino acids.
Source: Port Altele
